1. Field of the Invention
This invention relates to a bumper mounted on legs or other structural members of oil rig platforms for preventing damage by docked vessels or other floating objects.
2. General Discussion of the Background
Offshore drilling operations are often conducted from an elevated platform which is held in spaced relationship above the surface of the water by a plurality of legs supported by the ocean floor. Since it is necessary to bring food, supplies and personnel to the rig, boats often dock alongside the legs of the platform. These vessels and other free floating objects can seriously damage the legs of the platform, thereby endangering the structural integrity of the rig itself.
In order to avoid problems caused by damage to the legs, bumpers have been secured to the legs to provide a resilient structure in spaced, somewhat parallel relationship to the leg for preventing boats and other floating objects from damaging the leg. Examples of such bumpers are found in U.S. Pat. Nos. 4,005,672, 4,098,211, 4,109,474, 4,293,241, 4,273,473, 4,426,174 and 4,388,025. All of these patents disclose a vertically oriented bumper for a marine structure secured by a pair of parallel, horizontally disposed connection arms. These structures, however, suffer from several common defects.
In the first place, it is difficult and time consuming to orient the bumper vertically adjacent the leg of the platform. This difficulty is caused by the fact that the leg of the platform is always inclined at an angle to the vertical, and this angle is seldom the same on any two legs since the angle is determined by the specific floor conditions and other factors unique to this particular rig. It therefore becomes difficult to align a bumper vertically by connecting it with a pair of horizontal connection arms which are secured to the leg because the rigid horizontal connection arms must be of an appropriate length and relative angle to the bumper in order to achieve a vertical orientation of the bumper member.
Yet another problem with previously known structures is that the underwater horizontal connection arm must be welded to the leg of the platform underwater. Such subsurface welding requires several qualified divers who are experienced with welding. This means that initial installation or replacement of bumpers becomes a very time consuming and expensive procedure because of the requirement for underwater welding personnel.
Yet another problem with most prior art structures is that once the bumper is damaged, the entire bumper structure and horizontal connection arms must be removed and replaced. This results in greater cost of materials as well as an increase in personnel cost.
It is accordingly an object of this invention to provide a bumper attachment which can be easily vertically oriented in relation to the legs of offshore platforms which are frequently inclined at varying angles.
Another object of the invention is to provide a pivotal bumper attachment which reduces the necessity for employing subsurface welders.
Still another object of the invention is to provide a bumper attachment which requires only partial replacement after it is damaged.
Yet another object of the invention is to provide a bumper attachment which greatly reduces the amount of time required for replacement and repair of bumpers on oil rigs.
Still another object of the invention is to provide a bumper attachment that will not sink if it is damaged by impact from a vessel or other floating object.